Anatomical Variation of the Thyroid Gland - Levator glandulae thyroideae: A Case Report

Abstract

Surgical procedures on the thyroid are usually complicated by damage to the parathyroid glands, the external branch of superior laryngeal nerves, inferior laryngeal nerves, and hematoma due to vascular injury and the chance of residual thyroid tissue being left in case of cancer and Graves' disease, and the presence of anatomical variations. In this study, we describe the presence of a levator glandulae thyroideae that could misguide surgeons during surgical procedures.

Full text

Natalia M. Velasco-Nieves, et al. Journal of Health Sciences 2020;10(2):173-175 http://www.jhsci.ba
Journal of Health Sciences
CASE REPORT Open Access
Anatomical variation of the thyroid gland – Levator
glandulae thyroideae
Natalia M. Velasco-Nieves1, Adegbenro Omotuyi John Fakoya2*, Shannon Mathew1, Wirda
Zafar1, Mahrukh Zafar1, Kevin Alonso Milla1, Sushanth Yerra1, Abayomi Gbolahan Afolabi2,
Thomas McCracken2
1University of Medicine and Health Sciences, Basseterre, St. Kitts and Nevis, 2Department of Anatomy, University of
Medicine and Health Sciences, Basseterre, St. Kitts and Nevis
ABSTRACT
Surgical procedures are usually the treatment of choice when managing severe neck and thyroid-re-
lated pathologies; however, they become complicated by damage to the parathyroid glands, the external
branch of superior laryngeal nerves, inferior laryngeal nerves, and hematoma due to vascular injury and
the chance of residual thyroid tissue being left in case of cancer and Graves’ disease, and the presence of
anatomical variations. Therefore, prior knowledge of the incidence of anatomic anomalies would ensure
avoidance of such complications. In this study, we describe the presence of a levator glandulae thyroideae
that could misguide surgeons during surgical procedures.
Keywords: Levator glandulae thyroideae; thyroid; hyopyramidalis; thyroidectomy; pyramidal lobe
INTRODUCTION
e thyroid gland is a buttery-shaped endocrine
organ located in the anterior compartment of the
neck at the level C5 to T1 (1). It consists of two
lateral lobes connected by a narrow bridge known
as the isthmus. e thyroid gland is one of the most
important endocrine organs and plays a signicant
role in regulating metabolism, blood calcium levels,
growth, and development (1,2).
e size, shape, and structure of the thyroid gland
vary among individuals based on gender, race, and
age. Organogenesis of the thyroid gland occurs rst
in comparison to other endocrine organs during the
development of the embryo predisposing it to a wide
range of anomalies such as the presence of pyramidal
lobe and levator glandulae thyroideae (LGT), a bro-
muscular band (3,4). Other anomalies involving the
thyroid gland development include agenesis/absence of
isthmus and persistence of the thyroglossal ducts (1,3).
Among these anomalies, the persistence of thyroglossal
ducts and the presence of a pyramidal lobe are com-
mon, whereas agenesis of isthmus and presence of
LGT are rare and only a few cases have been reported
of such anomaly in the scientic literature (5).
LGT is classied into ve types based on their attach-
ment patterns: Hyopyramidalis, thyreopyramidalis,
thyreoglandularis, hyoglandularis, and tracheoglan-
dularis (1,2,6). LGT is a bromuscular band that
extends from the pyramidal lobe in most cases and
attaches to the hyoid bone located superiorly.
*Corresponding author: Adegbenro Omotuyi John Fakoya,
Department of Anatomy, University of Medicine and Health Sciences,
Basseterre, St. Kitts and Nevis. E-mail: afakoya@umhs-sk.net
Submitted: 24 March 2020/Accepted: 29 April 2020
DOI: https://doi.org/10.17532/jhsci.2020.904
© 2020 Natalia M. Velasco-Nieves, et al.; licensee University of Sarajevo - Faculty of Health
Studies. This is an Open Access article distributed under the terms of the Creative Commons
Attribution License (https://creativecommons.org/licenses/by/4.0/), which permits unre-
stricted use, distribution, and reproduction in any medium, provided the original work is
properly cited.
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174
http://www.jhsci.ba Natalia M. Velasco-Nieves, et al. Journal of Health Sciences 2020;10(2):173-175
In the case being discussed, we describe a hyopy-
ramidalis LGT that was discovered during routine
cadaveric dissection of head and neck region. In
the literature, there have been other researchers that
have reported a LGT originating from dierent sites
(Table1) (1,4,6,7,8,9).
CASE REPORT
During routine dissection of the neck of a 70-year-
old male Caucasian cadaver, at the Department of
Anatomy of the University of Medicine and Health
Sciences, St. Kitts and Nevis, a LGT was identied. It
was dissected carefully to look for any further attach-
ments and innervations above and below it. A thin
band of muscular bers stretched from the upper
middle border of the isthmus of the thyroid gland to
the body of the hyoid bone (Figure1). is type of
muscle bers would fall into hyopyramidalis classica-
tion of LGT as the bers were found to be extending
from the pyramidal lobe and attached to the hyoid
bone located above. No additional abnormalities were
found on the left and right lobes of the thyroid gland.
DISCUSSION
yroid diseases are a common health disorder
among endocrinopathies present in the world
population. Most of these diseases such as goiter,
thyrotoxicosis, adenoma, and carcinoma are usu-
ally associated with enlargement of the gland and
require medical and surgical intervention (4).
Our cadaver presented with the LGT muscle arising
from the superior border of the isthmus of the thyroid
TABLE 1. LGT origin reported in the literature
Authors Classication (8,9) Origin Year Reference
Loukas et al. Hyopyramidalis; thyreoglandularis;
hyoglandularis
Pyramidal lobe of thyroid gland – hyoid bone;
thyroid cartilage – thyroid gland; isthmus of thyroid
gland – hyoid bone
2008 (8)
Ranade et al. Hyoglandularis Isthmus of thyroid gland – hyoid bone 2008 (7)
Chaudhary Hyoglandularis Isthmus of thyroid gland – hyoid bone 2013 (1)
Muktyaz et al. Hyoglandularis Isthmus of thyroid gland – hyoid bone 2013 (4)
Sinha et al. Hyoglandularis Isthmus of thyroid gland – hyoid bone 2014 (6)
Present study Hyopyramidalis Pyramidal lobe of thyroid gland – hyoid bone 2019 -
LGT classication according to Mori (1964) (8,9)
FIGURE 1. The levator glandulae thyroideae is a bromuscular band or accessory muscle that originates from the isthmus of the thyroid
gland and attaches to the body of the hyoid bone (hyopyramidalis (8,9)), as seen in these images. LGT: Levator Glandulae Thyroideae;
I: Isthmus; LL: Left Lobe; RL: Right Lobe; H: Hyoid bone.

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Natalia M. Velasco-Nieves, et al. Journal of Health Sciences 2020;10(2):173-175 http://www.jhsci.ba
gland and attaching to the body of the hyoid bone.
e presence of this accessory muscle gains impor-
tance in the pathologies which are related to the thy-
roid gland and their treatment modalities due to its
proximity to the gland. Its occurrence is rare and only
very few cases have been reported in the medical liter-
ature (1). Due to anatomical variations in the muscle
tissues encompassing the thyroid organ, it is possible
to cause iatrogenic wounds during neck and thyroid
surgeries. In a study conducted to observe the thyroid
glands of cadavers for the presence of a LGT, approx-
imately 18.75% of the sample population were found
to have LGT (10). e variations of the LGT can be
associated with embryological disruption or anoma-
lies. One such example of this is the failure of the thy-
roid gland to descend correctly and regression of the
thyroglossal duct (3,11). is type of rare nding is
essential to identify and acknowledge during surgical
procedures carefully.
Eisler et al. conducted an extensive study regarding
the innervation of LGT and concluded that the
LGT must be innervated by either the ansa cervica-
lis or through the vagus nerve. Loukas et. al reported
(2008) that their cadaver’s LGT was innervated by a
branch of the ansa cervicalis (8). However, accord-
ing to a recent case report conducted by Chaudhary
et al. (2013), LGT may have dierent origins
regarding its innervation. Chaudhary et al. con-
cluded, after a close examination of their cadaver in
the study, that the LGT was innervated by branches
of the external laryngeal nerve (1).
Loukas et al. discussed the possible embryological
origin of the LGT depends on the location it must
have derived from. He reported the following pos-
sible sites he found in literature: e cricothyroid
muscle, the inferior pharyngeal constrictor muscle,
mastoid process, hyoid bone, thyroid cartilage, and
infrahyoid muscles, the last from which his cadaver’s
LGT was derived from according to its nerve supply.
Since the thyroid gland is a highly vascularized
structure, surgeons must be prepared to nd
this anatomical variation while carefully explor-
ing to ensure safe surgical procedures, such as
thyroidectomies (7,10). erefore, it is essential to
have a thorough understanding of the anterior cer-
vical region and its anatomical anomalies to avoid
any major complications in head and neck surgeries.
CONCLUSION
A rare anatomical variation associated with the thy-
roid gland is the presence of a LGT. We presented
a case of LGT during routine cadaveric dissection.
We also demonstrate the developmental and surgi-
cal implication of the anomaly and the importance
of having a thorough knowledge of anatomical vari-
ations to handle related clinical interventions with
condence.
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